Lecture 10 Flashcards
how are membranes moved from ER to other cellular components?
Enzyme modification
How can membranes change lipid composition?
enzyme modification to convert phospholipids
How are Lipids exchanged between organelles?
lipid transfer proteins
what do most Rough ER proteins become?
Glycoproteins
what catalyzes sugar addition to oligosaccharide?
Glycosyltransferase
what does the sugar arrangement on the oligosaccharide chains of glycoprotein depend on?
The spatial localization of enzymes
what are some properties of misfolded proteins?
Glucose tagged, mannose deficient and degraded by proteasomes
what does the accumulation of misfolded proteins trigger? How is it triggered? What occurs?
the unfolded protein response (UPR)
Occurs when BiP is prevented from inhibiting sensors
Sensors send signals to trigger proteins that destroy the misfolded proteins
What is the first step for vesicular transport from the ER? What occurs?
The Golgi Complex
Transport vesicles fuse with one another forming the ERGIC (ER Golgi intermediate counterpart) towards the Golgi complex
What is the Golgi complex composed of? What side faces where?
Stack of flattened cisternae
Cis Golgi side faces the ER
Trans Golgi side faces opposite side
What is the Cis Golgi network responsible for?
Sort proteins for the ER or next Golgi station
What is the trans side of the Golgi responsible for?
sorting proteins to the plasma membrane or intracellular destinations
True for False
The Golgi Complex is uniform in composition
False
What is used to carry materials between compartments?
Coated vesicles
What are the 2 functions of protein coats?
Curves the membrane to form vesicles
Select the components to be carried by vesicles
What are the 3 types of coated vesicle transport?
COPII, COPI and Clathrin
Where does COPI move materials? what kind of materials?
from ERGIC and Golgi back towards the ER (or trans Golgi -> Cis Golgi)
movement of escaped proteins back to ER
Where does COPII move materials? What does it bud off of? Where are the export signals from?
From the ER forwards to the ERGIC and Golgi complex
comes of the ER exit sites
Signals come from cytosolic tails of transported proteins
Where does Clathrin move materials?
from the TGN to endosomes, lysosomes and vacuoles
What do all vesicles have in common?
2 distinct layers; an outer and an inner
What are the differences between the 3 Vesicle transporters?
Clathrin outer layer overlap extensively
COPII does no over lap and consists of 4 edges over 3
What are COPI vesicles coat made of?
Coatamer, which is several proteins
What are organelle proteins maintained by?
Retention of resident molecules by being excluded from transport
retrieval of escaped proteins back into their normal compartment
How does escaped protein retrieval work?
specific receptors capture molecules, bring them to ER in COPI
Each membrane compartment has its own retrieval signal
Describe the synthesis of Integral Membrane Proteins on ER-Bound
Ribosomes.
▪ Know the functions of the RER.
▪ Describe the structure and functions of the Golgi complex.
▪ Distinguish the functions of the different types of vesicle transport.
